Redux lists middleware is a tool to manage the models (like User, Article, Product for instance) in your application in an optimized and simple way.

Installation

npm install --save redux-lists

The redux store should know how to handle actions coming from the redux-lists action creators. To enable this, we need to pass the redux-lists reducer to your store:

import { createStore, combineReducers } from 'redux';
import { reducer as reduxListsReducer } from 'redux-lists';

const rootReducer = combineReducers({
  // ...your other reducers here
  reduxLists: reduxListsReducer
});

const store = createStore(rootReducer);

Table of contents

• Motivations
• Concept in draw
• Case - a blog app

• Redux-lists in action
• Explanation
  • Files description
  • articleActions and articleSelectors
  • ArticleList workflow
  • ArticlePage workflow
• Redux state-tree sample
  • Redux-lists state-tree evolution

• API
  • getActionCreators(namespace, options)
  • getSelectors(namespace)

Motivations

Redux-lists is useful to:

• Factorize in a single place your models objects
• Do optimistic updates and improve your app responsiveness very easily
• Reduce the redux boilerplate: generates action creators + selectors to manage your model collections
• Improve code consistency

Concept in draw

Case - a blog app

In a blogging application, we probably will have... Articles ! Using redux, we will want to do the following operations in our app:

• Render a list of blog articles, with only their title and eventually a quick description
• Render a single blog article, with all it's information

If you are used to redux, you probably already are thinking about how you are going to store those objects in the state-tree, the action creators and the selectors that you will have to make to get that data from the tree.

Redux-lists in action

That's where redux-lists is useful, because it provides you those tools and even more!

For instance, in this case we want to manage a collection of articles. Redux-lists gives you action creators and selectors to manage those articles in your application.

Firstly, we need to generate those tools by giving redux-list the namespace you want them to operate in:

articleActions.js

import { getActionCreators } from 'redux-lists';

export const { setList: setArticleList, updateItems: updateArticles } = getActionCreators('ARTICLES');

articleSelectors.js

import { getSelectors } from 'redux-lists';

export const { listSelector: articlesListSelector, byKeySelector: articleByIdSelector } = getSelectors('ARTICLES');

Now, we want to write our ArticleList component. Here is the mechanism that we want to build here:

ArticleList.js

import React from 'react';
import { bindActionCreators } from 'redux';
import { connect } from 'react-redux';

import { setArticleList } from './articleActions.js';
import { articlesListSelector } from './articleSelectors.js';

class ArticleList extends React.Component {
    componentDidMount() {
        fetch('/articles')
            .then(response => response.json())
            .then(articles => {
                this.props.setArticleList(articles, 'ALL');
            });
    }
    
    render() {
        const { articles } = this.props;
        if (!articles) return 'Loading';
        if (articles.length === 0) return 'No articles yet !';
        
        return (
            <ul>
                {articles.map(article =>
                    <li key={article.id}>
                        {article.label}
                        {article.description}
                    </li>
                )}
            </ul>
        )
    }
}

function mapStateToProps(state) {
    return {
        articles: articlesListSelector(state, 'ALL')
    }
}

function mapDispatchToProps(dispatch) {
    return {
        setArticleList: bindActionCreators(setArticleList, dispatch)
    }
}

export default connect(mapStateToProps, mapDispatchToProps)(ArticleList);

Now let's consider we clicked on an article item in the list because we want to access this article page.

Here is a possible workflow for the ArticlePage component:

Note : We just performed an optimistic update ! Keep in mind that this behaviour is not mandatory to use with redux-list, but if you want to use such a mechanism redux-list makes it easy for you.

ArticlePage.js

import React from 'react';
import { bindActionCreators } from 'redux';
import { connect } from 'react-redux';

import { updateArticles } from './articleActions.js';
import { articleByIdSelector } from './articleSelectors.js';

class ArticlePage extends React.Component {
    componentDidMount() {
        fetch(`/articles/${this.props.id}`)
            .then(response => response.json())
            .then(article => {
                this.props.updateArticles(article);
            });
    }
    
    render() {
        const { article } = this.props;
        if (!article) return 'Loading';
        
        return (
            <article>
                <h1>{article.label}</h1>
                <h2>{article.author}</h2>
                <h3>{article.createdAt}</h3>
                
                <p>{article.content}</p>
            </article>
        )
    }
}

function mapStateToProps(state, ownProps) {
    const articleId = ownProps.id;
    return {
        article: articleByIdSelector(state, articleId)
    }
}

function mapDispatchToProps(dispatch) {
    return {
        updateArticles: bindActionCreators(updateArticles, dispatch)
    }
}

export default connect(mapStateToProps, mapDispatchToProps)(ArticlePage);

Detailed explanations

Let's take some time here to process and understand what is happening here.

Files description

• articleActions.js

If you are familiar to redux, you know what this is. If you don't, you should learn how redux works first.

• articleSelectors.js

Contains functions (memoized) that go through the redux state-tree to get information in it.

• ArticleList.js

A react component that fetches and renders a list of articles.

• ArticlePage.js

A react component that fetches and renders a blog article page.

articleActions and articleSelectors

In articleActions, we create the setArticleList and updateArticles redux-lists actions.

getActionCreators takes two parameters, the first being the namespace and the second being an options object.

Indeed, the model's objects (here the articles) are going to be stored in the state tree @@redux-lists/namespace (here @@redux-lists/ARTICLES).

Because of this, we also need to create the redux-lists articleSelectors in giving it the namespace they will have to look in: getSelectors('ARTICLES').

ArticleList workflow

When the ArticleList component is mounted, an AJAX request is performed to get the articles from the server.

When this request is fulfilled, we store those articles in a list called 'ALL' in dispatching setArticleList action.

Note: We will see how this list is structured in the redux state-tree right after, just keep in mind that we store the articles in a named list for now.

The state-tree gets updated, the mapStateToProps function is called. We use the articlesListSelector to get the articles we stored in redux. articlesListSelector takes the redux state and the listName we stored the articles in.

The articles are passed to our ArticleList and they are rendered in the UI.

ArticlePage workflow

Firstly, let's consider that the user has previously rendered the previous ArticleList to access to the ArticlePage.

When the ArticlePage component is getting mounted, mapStateToProps function is called. Since we already have some information about the article in the redux store (label, quick description), the articleByIdSelector finds them.

It means that the ArticlePage can render instantly and prepare the user for the rest of the information to be fetched if you want to.

When ArticlePage is mounted, an AJAX request is performed to get the article full information (it's content for instance).

When this request is fulfilled, we update the article already stored in redux in dispatching the updateArticles action.

The state-tree gets updated, the mapStateToProps function is called. Our articleByIdSelector gets our article with the new information we just fetched and ArticlePage re-renders.

Redux state-tree sample

To get a better grasp on what's happens with your objects when you set a redux-lists or when you make an update, let's see a sample redux-lists tree that could be produced in an application blog:

{
    "@@redux-lists": {
        "ARTICLES": {
          "list": {
            "ALL": ["article1", "article2", "article3"],
            "NEW": ["article3"],
            "AUTHOR=MANU": ["article1", "article2"],
            "AUTHOR=TOTO": ["article3"]
          },
          "map": {
            "article1": {
              "id": "article1",
              "label": "My first article !",
              "description": "This is my first article",
              "author": "MANU"
            },
            "article2": {
              "id": "article2",
              "label": "My second article !",
              "description": "This is my second article",
              "content": "Okay, this is my first article and it's about redux-lists!",
              "author": "MANU"
            },
            "article3": {
              "id": "article3",
              "label": "The third article",
              "description": "It's the third article of the blog but my first!",
              "author": "TOTO"
            }
          }
        }
    }
}

Redux-lists normalizes your array of objects into a map / list structure. This is pretty convenient because it avoids repetition of information, here the articles objects are in the map and their id used as a reference in the lists.

Redux-lists state-tree evolution

Let's consider this state-tree:

{
    "@@redux-lists": {
        "ARTICLES": {
          "list": {},
          "map": {}
        }
    }
}

And let's consider that fetch('/articles') returned those articles:

[
  {
    "id": "article1",
    "label": "My first article !",
    "description": "This is my first article",
    "author": "MANU"
  },
  {
    "id": "article2",
    "label": "My second article !",
    "description": "This is my second article",
    "author": "MANU"
  },
  {
    "id": "article3",
    "label": "The third article",
    "description": "It's the third article of the blog but my first!",
    "author": "TOTO"
  }
]

When we called setArticleList in our ArticleList component

this.props.setArticleList(articles, 'ALL');

here is what happened to redux-lists state tree:

{
    "@@redux-lists": {
        "ARTICLES": {
          "list": {
            "ALL": ["article1", "article2", "article3"]
          },
          "map": {
            "article1": {
              "id": "article1",
              "label": "My first article !",
              "description": "This is my first article",
              "author": "MANU"
            },
            "article2": {
              "id": "article2",
              "label": "My second article !",
              "description": "This is my second article",
              "author": "MANU"
            },
            "article3": {
              "id": "article3",
              "label": "The third article",
              "description": "It's the third article of the blog but my first!",
              "author": "TOTO"
            }
          }
        }
    }
}

API

getActionCreators(namespace, options)

• (String) namespace: A namespace for the map / lists of your model
• (Object) options: supported options are:
  • (String, default = 'id') onKey: The key used as reference for objects manipulations

getActionCreators returns an Object containing the keys:

• (Function) setList(items, listName): Adds items in the collection + places references in the list

  • (Array of objects) items: Model objects to be placed in the list. Object must at least have an unique identifier (id or the one defined by the above onKey)
  • (String) name of the list you want to place your objects in.

• (Function) updateItems(items): Upsert items in the collection

  • (Object or Array of objects) items: Places the objects into the redux-lists map

getSelectors(namespace)

• (String) namespace: A namespace for the map / lists of your model

getSelectors returns an Object containing the keys:

• (Function) listSelector(state, listName): Returns an array of objects previously put in the list with this listName
  • (Object) state: the entire redux state-tree
  • (String) listName: the list you want to extract the objects from
• (Function) byKeySelector(state, itemKey): Returns the object that have the itemKey key value (defined with getActionCreators)
  • (Object) state: the entire redux state-tree
  • (String) itemKey: the itemKey value of the object you want to read on the redux-lists store.

Note : The selectors are memoized so that if something has been processed / accessed once, it won't compute it again if it's asked another time with the same parameters.